The field sequential color display method is a typical known method for displaying colors, i.e. representation of colors, without using color filters. The field sequential system uses three colored light sources of red, green and blue, and monochromatic display elements to represent colors by switching three colored light sources at a high speed and synchronously displaying data with monochromatic display elements. Monochromatic display elements may be either reflection-type elements or transmission-type elements.
Color display devices of the field sequential type not using color filters are applied to liquid crystal displays. Further, field sequential projectors have been realized as commercially viable products because of some advantages, such as enabling a single-panel projector to attain a resolution equivalent to that of a three-panel projector not using the field sequential system, and simplifying the optical system. Furthermore, field sequential color display devices have been reported to be applied also to head-mounted displays that users can directly wear on their eyes because a compact and high-resolution color representation is possible.
In existing field sequential color display methods, red, green and blue light sources are sequentially turned ON and OFF at equal frequencies as shown in FIG. 2. For example, a round of lighting red→green→blue makes a unit period, and the unit period is repeated.
A color display method not using color filters, such as a field sequential system, needs display elements that can be switched very quickly. However, display elements tend to degrade in response when they are enhanced in resolution and enlarged in operative temperature range. Therefore, from the standpoint of the display elements, the switching cycle is preferably longer.
Regarding color display devices using the field sequential system, it is generally appreciated that users will sense flickers unless the ON/OFF frequency of each light source among red, green and blue light sources is shorter than 1/60 second. This means that individual display elements must be switched at a frequency shorter than 1/180 second, and this is against the requirement of a longer switching cycle as explained above.
It is therefore an object of the invention to provide a color display method and a color display device capable of preventing the problem of flickers even under a longer switching cycle of display elements.
A further object of the invention is to provide a color display method and a color display apparatus with which users are unlikely to sense flickers from color representation under the same switching cycle of display elements.
A still further object of the invention is to provide a color display method and a color display apparatus that can remove user-conscious flickers from field sequential color representation, even under a relatively long switching cycle of display elements.